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core_unreal: Fix deadlock with T.38 control frames. 

When using the ast_unreal_lock_all function no channel
locks can be held before calling it.

This change unlocks the channel that indicate was
called on before doing so and then relocks it afterwards.

ASTERISK-29035

Change-Id: Id65016201b5f9c9519a216e250f9101c629e19e9
This commit is contained in:
Joshua C. Colp 2021-03-19 10:52:08 -03:00 committed by Joshua Colp
parent 720a39eb9e
commit 73a52c53ce
1 changed files with 4 additions and 0 deletions
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4
main/core_unreal.c
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@ -710,6 +710,7 @@ int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data
* signaling and we need to be sure that the locking order is the same to prevent possible
* deadlocks.
*/
ast_channel_unlock(ast);
ast_unreal_lock_all(p, &chan, &owner);
if (owner) {
@ -726,12 +727,14 @@ int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data
}
ao2_unlock(p);
ast_channel_lock(ast);
} else if (parameters->request_response == AST_T38_TERMINATED) {
/*
* Lock both parts of the local channel so we can restore their topologies to the original.
* The topology should be on the unreal_pvt structure, with a ref that we can steal. Same
* conditions as above.
*/
ast_channel_unlock(ast);
ast_unreal_lock_all(p, &chan, &owner);
if (owner) {
@ -745,6 +748,7 @@ int ast_unreal_indicate(struct ast_channel *ast, int condition, const void *data
}
ao2_unlock(p);
ast_channel_lock(ast);
}
/*